The rainbow darter is easily identified by three dark spots on the back, and blue and orange in the dorsal and anal fins.

In particular, it is common throughout the eastern United States, specifically throughout the Great Lakes and Ohio River Valley regions.

In Four-Mile Creek in Ohio, the rainbow darter lives primarily on trichopterans (i.e. caddisflies), having two feeding peaks: one in the morning and a second in the late afternoon or early evening.

[7] Because E. caeruleum has such a low tolerance for brackish water, human-induced changes such as pollution or sewer drainage has the potential to cause a significant negative impact on its abundance.

[3] This darter also displays group spawning, and the males tend to exhibit territorial behavior during the breeding season.

[9] Currently, the largest threat to E. caeruleum is run-off and pollution due to the population shift from rural to urban areas.

One study found the development of an interstate highway negatively affected the abundance of several fish species, including E. caeruleum, because of decreasing quality of water of the nearby creek.